Electric vehicle thermal management system with series and parallel structure

ABSTRACT

Electric vehicle thermal management systems and electric vehicles using the thermal management system, are disclosed. A passenger cabin is heated by the heat dissipated from a battery and/or a motor. A cooling circuit in the management system fluidly connects the battery, the motor and a first radiator in series. The first radiator provides a heat source to the passenger cabin by means of the heat dissipated from the battery and/or the electric motor. Under certain conditions, the electric motor is selectively separated from the cooling circuit, so that when the passenger cabin needs to be heated, the thermal management system can provide heat to the passenger cabin without affecting the heat dissipation of the battery.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to U.S. Provisional Patent Application No. 62/133,991, filed on Mar. 16, 2015, and U.S. Provisional Patent Application No. 62/150,848, filed on Apr. 22, 2015, the disclosures of which are hereby incorporated by reference in their entireties for all purposes.

BACKGROUND

Exemplary embodiments of the present disclosure relate to thermal management systems for vehicles, and particularly relate to the field of electric vehicles.

A battery can be used as the power source of an electric vehicle, and the endurance mileage of the electric vehicle is a particularly important aspect of the vehicle. The temperature in a passenger cabin of an existing electric vehicle is generally adjusted by an air conditioning system, in order to maintain the temperature in the passenger cabin within a range that makes people feel comfortable. The battery is also used as the energy source of the air conditioning system, and this generally consumes more battery energy to influence the endurance mileage of the electric vehicle.

SUMMARY

In view of the above problems, aspects of the present disclosure are intended to provide an electric vehicle thermal management system, which may be used for effectively saving the electric power of electric vehicles, and electric vehicles using such thermal management systems.

According to a first aspect of the disclosure, an electric vehicle thermal management system for heating a passenger cabin of an electric vehicle by means of heat absorbed from a battery and/or an electric motor of the electric vehicle is provided. The thermal management system may include one or more of a cooling circuit used for circulating cooling liquid, wherein a battery, an electric motor and a first radiator are fluidly connected in series in the cooling circuit, so that the cooling liquid in the cooling circuit can cool the battery and/or the electric motor to absorb heat. In embodiments, the first radiator may provide a heat source to the passenger cabin by dissipating the heat absorbed by the cooling liquid. In embodiments, the electric motor may be selectively separated from the cooling circuit.

In embodiments, the cooling circuit may include a first part path fluidly connecting the battery and the first radiator, wherein the first part path is provided with a first part path inlet for the inflow of the cooling liquid and a first part path outlet for the outflow of the cooling liquid. In embodiments, the cooling circuit may include a second part path fluidly connecting the electric motor, wherein the second part path is provided with a second part path inlet for the inflow of the cooling liquid and a second part path outlet for the outflow of the cooling liquid. The system may also include a switching device configured to connect the first part path outlet with the second part path inlet and connect the second part path outlet with the first part path inlet at the first state, so as to fluidly connect the battery, the electric motor and the first radiator in series. The switching device may also be configured to connect the first part path outlet with the first part path inlet at the second state, so as to separate the electric motor from said cooling circuit.

In some examples, the switching device may connect the second part path outlet with the second part path inlet at the second state, so that the electric motor is connected to another cooling circuit independent from said cooling circuit.

In some examples, the electric motor may be connected to another cooling circuit, independent from said cooling circuit, after the electric motor is separated from the cooling circuit.

In some examples, the first radiator can be separated from said cooling circuit when the passenger cabin does not need to be heated.

Embodiments may also include a controller configured to control the switching device to switch between the first state and the second state according to the working condition of the battery.

Embodiments may also include a second radiator, wherein the second radiator is arranged to dissipate heat to the outside of the vehicle, and the second radiator is selectively connected in the second part path.

Embodiments may also include a refrigerator for exchanging heat with the first part path. In some embodiments, the refrigerator may be selectively separated from the first part path according to, for example, the temperature of the battery.

According to further aspects of the disclosure, an electric vehicle is provided, including a thermal management system as described herein.

Compared with other methods, embodiments of the disclosure may provide, at least in part, advantages such as effective heat dissipation of the components which generate heat, and meanwhile, the heat generated by the components are effectively transmitted to the passenger cabin, so as to heat the passenger cabin when necessary. Therefore, the electric power of the electric vehicle can be effectively saved to increase the endurance mileage of the electric vehicle.

Additional features, advantages, and embodiments of the invention may be set forth or apparent from consideration of the following detailed description, drawings, and claims. Moreover, it is to be understood that both the foregoing summary of the invention and the following detailed description are exemplary and intended to provide further explanation without limiting the scope of the invention claimed. The detailed description and the specific examples, however, indicate only preferred embodiments of the invention. Various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the invention, are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the detailed description serve to explain the principles of the invention. No attempt is made to show structural details of the invention in more detail than may be necessary for a fundamental understanding of the invention and various ways in which it may be practiced. In the drawings:

FIG. 1 shows a structural block diagram of a first working mode of an electric vehicle thermal management system according to an embodiment of the disclosure;

FIG. 2 is a more detailed schematic view of the first working mode in FIG. 1;

FIG. 3 shows a structural block diagram of a second working mode of the electric vehicle thermal management system according to an embodiment of the disclosure;

FIG. 4 is a more detailed schematic view of the second working mode in FIG. 3;

FIG. 5 shows a control block diagram of the electric vehicle thermal management system according to an embodiment of the disclosure;

FIG. 6 shows a structural block diagram of a third working mode of the electric vehicle thermal management system according to an embodiment of the disclosure; and

FIG. 7 shows a structural block diagram of a fourth working mode of the electric vehicle thermal management system according to an embodiment of the disclosure.

DETAILED DESCRIPTION

Various example embodiments of the present disclosure will be described below with reference to the drawings constituting a part of the description. It should be understood that, although terms representing directions are used in the present disclosure, such as “front”, “rear”, “upper”, “lower”, “left”, “right”, and the like, for describing various exemplary structural parts and elements of the present disclosure, these terms are used herein only for the purpose of convenience of explanation and are determined based on the exemplary orientations shown in the drawings. Since the embodiments disclosed by the present disclosure can be arranged according to different directions, these terms representing directions are merely used for illustration and should not be regarded as limiting. Wherever possible, the same or similar reference marks used in the present disclosure refer to the same components.

Unless defined otherwise, all technical terms used herein have the same meanings as commonly understood by one of ordinary skill in the art to which the invention pertains. The embodiments of the invention and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments and examples that are described and/or illustrated in the accompanying drawings and detailed in the following description. It should be noted that the features illustrated in the drawings are not necessarily drawn to scale, and features of one embodiment may be employed with other embodiments as the skilled artisan would recognize, even if not explicitly stated herein. Descriptions of well-known components and processing techniques may be omitted so as to not unnecessarily obscure the embodiments of the invention. The examples used herein are intended merely to facilitate an understanding of ways in which the invention may be practiced and to further enable those of skill in the art to practice the embodiments of the invention. Accordingly, the examples and embodiments herein should not be construed as limiting the scope of the invention, which is defined solely by the appended claims and applicable law. Moreover, it is noted that like reference numerals reference similar parts throughout the several views of the drawings.

Exemplary electric vehicle thermal management systems according to aspects of the present disclosure may be capable of supplying heat to a passenger cabin by means of the heat dissipation of a battery and an electric motor of an electric vehicle. For example, such thermal management systems may be configured connect a cooling liquid flow path of the battery and/or the electric motor to a radiator capable of dissipating heat into the passenger cabin, and the radiator supplies heat to the passenger cabin through the heat absorbed by cooling liquid from the battery and/or the electric motor. The thermal management systems may have a variety of working modes, which are determined by whether the passenger cabin needs heat supply and/or whether the temperature of the battery exceeds a normal working range.

Various working modes of thermal management systems according to the present disclosure will be described below in detail with reference to the accompanying drawings.

FIG. 1 to FIG. 4 show various working modes of an exemplary thermal management system according to aspects of the present disclosure when the passenger cabin needs heat supply.

Reference is now made to FIG. 1. FIG. 1 shows a structural block diagram of the first working mode of an exemplary thermal management system according to aspects of the present disclosure. According to FIG. 1, a first radiator 104 is arranged near a passenger cabin 1, the heat dissipated from the first radiator heats the passenger cabin 1, and the heat source of the first radiator 104 is from the heat dissipated from the battery 101 and the electric motor 102 of the electric vehicle. The electric vehicle thermal management system includes a cooling circuit used for circulating cooling liquid, wherein the battery 101, the electric motor 102 and the first radiator 104 are fluidly connected in series in the cooling circuit, so that the cooling liquid in the cooling circuit can cool the battery 101 and the electric motor 102 and transmit the heat dissipated from the battery 101 and the electric motor 102 to the first radiator 104, so as to supply heat to the passenger cabin 1 through the first radiator 104.

The battery 101 and the electric motor 102 are connected in series in the cooling circuit to effectively transmit the heat of two components which generate heat to the first radiator 104, in order to quickly heat the passenger cabin, so that the heating efficiency is high. This is particularly useful when the environment temperature is low.

FIG. 3 shows a structural block diagram of a second working mode of an exemplary thermal management system according to aspects of the present disclosure. In this embodiment, the electric motor 102 is separated from the cooling circuit where the first radiator as shown in FIG. 1 is connected. At that time, in the cooling circuit where the first radiator is connected, only the first radiator 104 and the battery 101 are connected in series, and the first radiator 104 heats the passenger cabin 1 via the heat dissipated from the battery 101.

This working mode may be selected, for example, according to the temperature of the battery. Since the battery 101 may be very sensitive to temperature, the heat dissipation of the battery 101 may need to be preferentially guaranteed. Normally, the passenger cabin 1 can be simultaneously heated by the heat dissipated from the battery 101 and the electric motor 102, but when the temperature of the battery is relatively high, in order to ensure the effective heat dissipation of the battery 101, separating the electric motor 102 from the cooling circuit can effectively shorten the heat dissipation circuit of the battery 101 and prevent the heat of the electric motor 102 from influencing the heat dissipation of the battery 101, and meanwhile, since the battery 101 continues to provide heat to the first radiator 104, the heat supply of the passenger cabin 1 is still well guaranteed. In this working mode, the heat of the component which generates heat (namely the battery) is effectively transmitted to the passenger cabin 1 without affecting the heat dissipation of the component.

After the electric motor 102 is separated from the cooling circuit where the first radiator is connected, the electric motor 102 may dissipate heat through another cooling circuit 108 independent from the cooling circuit where the first radiator is connected. This guarantees that the heat of the electric motor 102 can be dissipated after it is separated from the cooling circuit, and the heat dissipation of the battery is not influenced by the heat of the electric motor 102.

Reference is made now to FIG. 6 and FIG. 7. FIG. 6 and FIG. 7 respectively show a third working mode and the fourth working mode of an exemplary thermal management system according to aspects of the present disclosure. At the two working modes, since the passenger cabin does not need heat supply due to a higher environment temperature, the first radiator 104 is separated from the cooling circuit. In the third working mode as shown in FIG. 6, the first radiator 104 is separated from the cooling circuit, and the battery 101 and the electric motor 102 are connected in series in the cooling circuit. In the fourth working mode as shown in FIG. 7, the first radiator 104 is separated from the cooling circuit, and the battery 101 and the electric motor 102 are respectively connected in two independent cooling circuits. When the temperature of the battery 101 is normal, the thermal management system may operate at the third working mode, and when the temperature of the battery 101 is too high, the thermal management system may be switched to the fourth working mode.

Some components that may be used in exemplary cooling circuits of the thermal management system are described below in order to illustrate how the above-mentioned various working modes may be switched.

Looking at FIG. 1 and FIG. 2 first, FIG. 2 shows a more detailed schematic view of the first working mode in FIG. 1. As shown in FIG. 1, the cooling circuit includes a first part path (A), and the first part path (A) fluidly connects the battery 101 and the first radiator 104. As shown in FIG. 2, the first part path (A) is provided with a first part path inlet 1052 for the inflow of the cooling liquid and a first part path outlet 1051 for the outflow of the cooling liquid. The cooling circuit further includes a second part path (B), wherein the second part path (B) fluidly connects the electric motor 102, and the second part path (B) is provided with a second part path inlet 1054 for the inflow of the cooling liquid and a second part path outlet 1053 for the outflow of the cooling liquid. The first part path (A) and the second part path (B) are connected and separated by a switching device 105.

Specifically, the switching device 105 has two states, FIG. 2 shows the first state of the switching device 105, and FIG. 4 shows the second state of the switching device. At the first state as shown in FIG. 2, the switching device 105 connects the first part path outlet 1051 with the second part path inlet 1054 and connects the second part path outlet 1053 with the first part path inlet 1052, so as to connect the first part path (A) with the second part path (B), namely, the battery 101, the electric motor 102 and the first radiator 104 are connected in series in the cooling circuit. At the second state as shown in FIG. 4, the switching device 105 connects the first part path outlet 1051 with the first part path inlet 1052 so as to separate the first part path (A) from the second part path (B), namely, the electric motor 102 is separated from the cooling circuit of the battery. At the second state, the switching device 105 further connects the second part path outlet with the second part path inlet so as to form another cooling circuit for independently cooling the electric motor 102. Thus, the thermal management system may be switched to the second working mode as shown in FIG. 3.

The switching device 105 can be selected, for example, from a four-way valve or the combination of multiple three-way valves.

As shown in FIG. 2 and FIG. 4, pumps 103, 103′ are respectively connected in the first part path (A) and the second part path (B) for conveying the cooling liquid to the components to be cooled in the paths and determining the flow rate of the cooling liquid in the paths. A cooling liquid source 109 may be connected with the cooling circuit and used for supplementing the cooling liquid for the cooling circuit when the cooling liquid in the cooling circuit is lost.

The first radiator 104 is connected with the cooling circuit through a switch 113. At the two working modes as shown in FIG. 1 and FIG. 3, the switch 113 is turned on to connect the first radiator 104 into the cooling circuit, so as to supply heat to the passenger cabin. When the passenger cabin does not need heat supply, the switch 113 may be turned off, so as to separate the first radiator 104 from the cooling circuit. At that time, the thermal management system can be in the working modes as shown in FIG. 6 and FIG. 7.

As shown in FIG. 2 and FIG. 4, a second radiator 108 may also be provided in the thermal management system. The second radiator 108 is arranged to selectively connected in the cooling circuit to dissipate the heat absorbed from the cooling circuit to the outside of the vehicle. When the second radiator 108 is connected in the cooling circuit, the thermal management system can be in the working modes as shown in FIG. 6 and FIG. 7.

Reference is made to FIG. 2 and FIG. 4 again, in which the second radiator 108 is connected to the second part path (B) through a switch 112. When the switch is turned on, the second radiator 108 may be connected with the second part path (B), and then, the thermal management system can be in the working modes as shown in FIG. 6 and FIG. 7. When the switch is turned off, the second radiator 108 may be disconnected with the second part path (B), and then, the thermal management system can be in the working modes as shown in FIG. 1 and FIG. 3.

For the working mode as shown in FIG. 6, the battery 101, the electric motor 102 and the second radiator 108 are connected in series, and the heat of the battery 101 and the electric motor 102 are dissipated to the outside of the vehicle by the second radiator 108; for the working mode as shown in FIG. 7, the electric motor 102 and the second radiator 108 are connected in series in the second part path, while the heat of the battery 101 is not dissipated to the outside of the vehicle by the second radiator 108, and only the heat of the electric motor 102 is dissipated to the outside of the vehicle by the second radiator 108.

Reference is still made to FIG. 2 and FIG. 4, which show an example of a refrigerator 106 that may also be provided in the thermal management system, e.g. for being selectively connected in the cooling circuit according to the temperature of the battery. The refrigerator 106 can cool the cooling liquid in the cooling circuit to enable the cooling liquid to better cool the components which have high temperature. Since the battery 101 has a higher requirement on the working temperature compared with other components, for example, the electric motor 102, the refrigerator 106 is preferably arranged to be selectively connected with the first part path (A), in order to quickly cool the battery 101 when the temperature of the battery 101 is too high. For example, the refrigerator 106 may be connected to the first part path (A) through a switch 111, and when the temperature of the battery 101 is too high and the cooling liquid needs to be cooled, the switch 111 may be turned on to connect the refrigerator 106 in the first part path (A); when the cooling liquid does not need to be cooled, the switch 111 may be turned off to separate the refrigerator 106 from the first part path (A). In other embodiments, the refrigerator 106 can be connected to other positions of the cooling circuit.

The switch 113, the switch 111 and the switch 112 can use, for example, three-way valves. The switch 113 and the switch 111 may be constituted, for example, from two three-way valves.

A heater 107 may also be provided in the thermal management system, and the heater 107 may be connected in the first part path (A) to selectively heat the cooling liquid flowing to the battery. Specifically, the heater 107 is arranged upstream of the battery 101, namely, the cooling liquid firstly flows through the heater 107 and then flows through the battery 101, and a control device 201 controls the heater 107 to start or stop, in order to select to heat the cooling liquid or not. Due to this arrangement, the battery 101 can be quickly heated when the temperature of the battery 101 is low.

Besides the electric motor 102, other components 110 which can generate heat in the electric vehicle, for example, a charger and the like, can also be connected in the second part path (B) so that the other components 110 which can generate heat can be cooled by the second part path. When the switching device 105 is at the first state, the heat of the other components 110 which can generate heat is also transmitted to the first radiator 104 to provide heat to the passenger cabin 1.

The control flow of an exemplary electric vehicle thermal management system according to aspects of the present disclosure will be illustrated below with reference to the control block diagram of the electric vehicle thermal management system as shown in FIG. 5. As shown in FIG. 5, a passenger cabin temperature sensor 204, a battery temperature sensor 203, a motor temperature sensor 202 and the control device 201 may be provided in the electric vehicle thermal management system. The passenger cabin temperature sensor 204, the battery temperature sensor 203 and the motor temperature sensor 202 respectively detect the temperatures of the passenger cabin, the battery and the motor and transmit the detected temperatures to the control device 201. The control device 201 controls the actions of the pump 103, the switching device 105, the switch 111, the switch 112, the switch 113 and the heater 107 according to comprehensive judgments of temperatures of the devices and an external passenger instruction, so as to switch the thermal management system among the various working modes.

When the vehicle is at a normal running state, the control device 201 firstly determines to connect the first radiator 104 in the cooling circuit or connect the second radiator 108 in the cooling circuit according to an instruction sent by the passenger indicating whether the passenger cabin need heat supply.

Normally, if an instruction from the passenger indicating whether the passenger cabin need heat supply has not been received, the second radiator 108 is connected in the cooling circuit to dissipate the heat absorbed by the cooling circuit to the outside of the vehicle, while the first radiator 104 is separated from the cooling circuit.

When the passenger sends an instruction indicating to supply heat to the passenger cabin, the control device 201 controls the switch 112 of the second radiator 108 to turn off to separate the second radiator 108 from the cooling circuit, and controls the switch 113 of the first radiator 104 to turn on to connect the first radiator 104 in the cooling circuit. Then, the control device 201 judges whether the battery 101 and the electric motor 102 are within normal working temperature ranges according to the temperatures detected by the battery temperature sensor 203 and the motor temperature sensor 202. If it is judged that both the battery 101 and the electric motor 102 are within the normal working temperature ranges, the control device 201 controls the switching device 105 to be at the first state, and then, the battery 101, the electric motor 102 and the first radiator 104 are fluidly connected in series, and the battery 101 and the electric motor 102 heat the passenger cabin 1 at the same time. When the temperature of the battery 101 exceeds the normal working temperature range, the control device 201 controls the switching device 105 to be at the second state and controls the switch 112 of the second radiator 108 to turn on, and then the battery 101 and the electric motor 102 are respectively connected in different cooling circuits, the first radiator 104 supplies heat to the passenger cabin by means of the temperature of the battery, and the heat of the motor 102 can be dissipated by the second radiator to the outside of the vehicle. At that time, the control device 201 can also control the switch 111 of the refrigerator 106 to turn on to connect the refrigerator 106 with the cooling circuit, in order to cool the cooling liquid flowing through the battery via the refrigerator 106 to further accelerate the cooling of the battery. Moreover, no matter whether the switching device 105 is at the first state or the second state, the control device 201 can judge whether there is a need to control the pumps 103, 103′ to accelerate according to the temperatures of the battery 101 and the electric motor 102, in order to accelerate the flow rate of the cooling liquid in the cooling circuit to speed up the cooling rate.

When the vehicle is just started, according to the temperature of the battery 101, the control device 201 further needs to judge whether there is a need to heat the battery, in order to quickly heat up the battery to a degree that is enough for the battery to operate normally. If it is judged that the battery needs to be heated, the control device 201 controls the heater 107 to start, the heat of the heater 107 will help to heat the battery 101, at that time, the switching device 105 is controlled and switched to the second state, namely the battery 101 and the electric motor 102 are respectively connected in different cooling circuits, in order to prevent the heat of the heater 107 from influencing the temperature of the electric motor 102.

In addition, when the temperature of the passenger cabin is low or when the passenger instructs to heat the passenger cabin, the control device 201 can control the heater 107 to start, and the heat provided by the heater 107 will also supply heat to the passenger cabin 1.

According to the instruction sent by the passenger indicating not to supply heat to the passenger cabin, the control device 201 can also control the switch 113 of the first radiator 104 to turn off to separate the first radiator 104 from the cooling circuit and control the switch 112 of the second radiator 108 to turn on to connect the second radiator 108 in the cooling circuit.

By adopting the above-mentioned heat exchange system, various embodiments of the present disclosure may supply heat to the passenger cabin by using the heat absorbed by the cooling liquid from the battery and/or the electric motor, so that the electric power of the electric vehicle can be effectively utilized to increase the endurance mileage of the electric vehicle.

The present disclosure further provides an electric vehicle using the above-mentioned vehicle thermal management system, the other parts of the electric vehicle can adopt the structure of existing electric vehicles, with a vehicle thermal management system as described herein, and will not be repeated redundantly.

Although the present disclosure has been described with reference to the specific embodiments shown in the drawings, it should be understood that the lightweight fastening methods provided by the present disclosure can have a variety of variations without departing from the spirit, scope and background of the present disclosure. The description given above is merely illustrative and is not meant to be an exhaustive list of all possible embodiments, applications or modifications of the invention. Those of ordinary skill in the art should be still aware that, parameters in the embodiments disclosed by the present disclosure can be changed in different manners, and these changes shall fall within the spirit and scope of the present disclosure and the claims. Thus, various modifications and variations of the described methods and systems of the invention will be apparent to those skilled in the art without departing from the scope and spirit of the invention. 

What is claimed is:
 1. An electric vehicle thermal management system for heating a passenger cabin of an electric vehicle by means of heat absorbed from at least one of a battery and an electric motor of the electric vehicle, the electric vehicle thermal management system comprising: a first radiator; a switching device; and a cooling circuit for circulating cooling liquid; and, wherein the battery, the electric motor and the first radiator are fluidly connected in series in the cooling circuit, so that the cooling liquid in the cooling circuit cools the battery and the electric motor by absorbing heat; the first radiator is configured to provide a heat source to the passenger cabin by dissipating the heat absorbed by the cooling liquid; the cooling circuit comprises: a first part path fluidly connecting the battery and the first radiator, wherein the first part path is provided with a first part path inlet for the inflow of the cooling liquid and a first part path outlet for the outflow of the cooling liquid; and a second part path fluidly connecting the electric motor, wherein the second part path is provided with a second part path inlet for the inflow of the cooling liquid and a second part path outlet for the outflow of the cooling liquid; and the switching device is configured to: connect the first part path outlet with the second part path inlet and connect the second part path outlet with the first part path inlet at a first state, so as to fluidly connect the battery, the electric motor and the first radiator in series; and connect the first part path outlet with the first part path inlet at a second state, so as to separate the electric motor from said first radiator in said cooling circuit while fluidly connecting the battery and the first radiator in series.
 2. The system of claim 1, wherein the switch device is configured such that: after the electric motor is separated from the cooling circuit by the switch device, the electric motor is connected to another cooling circuit independent from said cooling circuit by the switching device.
 3. The system of claim 1, wherein: in response to an indication that the passenger cabin does not need to be heated, the first radiator is configured to be separated from said cooling circuit.
 4. The system of claim 3, wherein: in response to an indication that the first radiator is separated from said cooling circuit, the motor and the battery are at least one of connected in said cooling circuit or respectively connected in different cooling circuits.
 5. The system of claim 1, wherein the switching device connects the second part path outlet with the second part path inlet at the second state, so that the electric motor is connected to another cooling circuit independent from said cooling circuit.
 6. The system of claim 5, further comprising: a controller, wherein the controller is configured to control the switching device to switch between the first state and the second state according to the working condition of the battery.
 7. The system of claim 5, further comprising: a refrigerator for exchanging heat with the first part path, wherein the refrigerator is configured to be selectively separated from the first part path according to the temperature of the battery.
 8. The system of claim 5, further comprising: a second radiator, wherein the second radiator is arranged to dissipate heat to the outside of the vehicle, and the second radiator is selectively connected in the second part path.
 9. The system of claim 5, further comprising: a heater, wherein the heater is connected in the first part path; and, wherein the control device is further configured to control the heater to start or stop.
 10. The system of claim 1, further comprising: a controller, wherein the controller controls the switching device to switch between the first state and the second state according to the working condition of the battery.
 11. The system of claim 1, further comprising: a cooling liquid source connecting with the cooling circuit for supplementing cooling liquid to the cooling circuit.
 12. The system of claim 1, further comprising: a refrigerator for exchanging heat with the first part path; the refrigerator is selectively separated from the first part path according to the temperature of the battery.
 13. The system of claim 1, further comprising: a second radiator, wherein the second radiator is arranged to dissipate heat to the outside of the vehicle, and the second radiator is selectively connected in the second part path.
 14. The system of claim 1, further comprising: a heater, wherein the heater is connected in the first part path; the control device controls the heater to start or stop.
 15. An electric vehicle, comprising: a passenger cabin; a battery; an electric motor configured to be powered by the battery; and a thermal management system configured for heating the passenger cabin by means of heat absorbed from at least one of the battery or the electric motor, the thermal management system including a cooling circuit used for circulating cooling liquid, wherein the battery, the electric motor and a first radiator are fluidly connected in series in the cooling circuit, so that the cooling liquid in the cooling circuit can cool the battery and the electric motor to absorb heat, wherein, the first radiator is configured to provide a heat source to the passenger cabin by dissipating the heat absorbed by the cooling liquid; the cooling circuit comprises: a first part path fluidly connecting the battery and the first radiator, wherein the first part path is provided with a first part path inlet for the inflow of the cooling liquid and a first part path outlet for the outflow of the cooling liquid; and a second part path fluidly connecting the electric motor, wherein the second part path is provided with a second part path inlet for the inflow of the cooling liquid and a second part path outlet for the outflow of the cooling liquid; and the thermal management system further comprises a switching device configured to: connect the first part path outlet with the second part path inlet and connect the second part path outlet with the first part path inlet at a first state, so as to fluidly connect the battery, the electric motor and the first radiator in series; and connect the first part path outlet with the first part path inlet at a second state, so as to separate the electric motor from said first radiator in said cooling circuit while fluidly connecting the battery and the first radiator in series.
 16. The vehicle of claim 15, wherein the switching device connects the second part path outlet with the second part path inlet at the second state, so that the electric motor is connected to another cooling circuit independent from said cooling circuit.
 17. The vehicle of claim 15, further comprising: a controller, wherein the controller is configured to control the switching device to switch between the first state and the second state according to the working condition of the battery. 